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Tornado near Coonabarabran 2005 Jan 20

This tornado formed at 4:30pm during a severe thunderstorm and ran a path of over 5km towards the SE. It crossed the Oxley Highway near the end of its path where a car and a truck were forced to stop, becoming trapped by falling trees. The car sustained a broken window. In the adjoining paddocks six sheep and one cow were killed with several other animals injured.

The following notes are compiled largely from eye-witnesses and will be updated and expanded over the next week. Additional information is being sought and anyone with sightings, photos or video is requested to contact Rob McNaught at rmn@mso.anu.edu.au.

Sat Jan 29. Short update. It appears that the car trapped by fallen trees in front and behind, was some distance outside the tornado path. This has to be confirmed from photos taken at the time, but would explain why the car was not thrown off the road. The tornado was around 300m wide on crossing the Oxley Hwy and was probably on the ground for around 5 minutes after a long buildup. Please note the embedded links to Vivian Evans' stunning images of the tornado forming from the wall cloud. A major update of this web page will be made on Monday.

Sun Jan 30. Another short update. The tornado had 80% of it's path on the property of Ian Klein. He had significant stock losses, with a dozen sheep, three cows and a foal killed. Other animals were injured and may not survive. Ian suspects the cattle were lifted and dropped.

The start of the tornado was on the block of Craig and Gail Comyns in Stannix Park. They were watching the storm build but then it became suddenly very silent. When the wind started again it rapidly became very violent so they gathered their children rushed into their house and lay on the floor and under beds. Their timber house was shaking violently, the roof was lifting and dropping, but remained intact. Trees were felled and branches are broken around their house, but the main damage was some 50 metres distant. After the firece winds subsided they went outside and saw the tornado to their SE moving away. It was some 100+m wide and black as burning rubber tyres. Trees were being plucked from the ground like someone weeding the garden. Inspection of the forest to their SE reveals the start of severe tree damage (comparable to the Oxley Highway damage detailed below) only 300m from their house. For a while, a second tornado appeared to the left of the main one and was about one quarter the diameter. It appeared and disappeared is if switched on and off with a switch. In contrast to the black of the main tornado, it was orange, suggestive of picking up only sandy soil in the open paddock it was crossing.

The first 20% and last 30% of the tornado path has now been well surveyed. Some of the middle 50% has been partially surveyed, but as much of this is open paddocks, there is not a lot left to do. The map of the damage path will be updated tomorrow.

There are reports that the tornado was visible from Coonabarabran 21km away and even Mullaley some 40km distant. Hopefully someone has obtained either video or stills of much of the tornado path.

The Wall Cloud

As the storm developed, it was watched by Charlie Harris and family from "South Burloo" and by Vivian and Brian Evans from Stannix Park. The descriptions are very consistent of the cloud rushing together from various directions and starting to rotate. The latter stages of the tornado's development are well documented in a series of astonishing images recorded by Vivian Evans. The first in the sequence, taken at 4:24pm, is shown below.

The developing wall cloud

Brian Evans watches the wall cloud develop to his SE.

The cloud base is seen here lowering into a rotating wall cloud. As the tornado developed it was largely hidden from view by the forest, despite being only a couple of kilometres away. Three more of Vivian's pictures of the developing tornado appear here.  Vivian's last photo was taken at 4:28pm.

Aerial views

To better assess the path of the tornado, Andre Phillips (UNSW Automated Patrol Telescope) flew Rob McNaught and Tanya Smith over the general area three days after the event. The two images below show the most visible damage along the Oxley Highway. It is so dramatic that many travellers, unaware of the tornado, stop and inspect the damage.

Aerial view to west

Looking west.

On the image above there is considerable ground scouring in the paddock to the right of the highway and significant tree damage on the hill to the far right. The location of Siding Spring Observatory is shown on the horizon some 37km distant.

Aerial view to east

Looking east.

After crossing the highway, there is no ground scouring for about 200m but then some intense scouring has removed a cover of grass and saffron thistle. From the description by Charlie Harris, it appears that the tornado looped at the end of it's ground path and the pattern of scouring may suggest this. The markings in the paddock at the bottom left of the image may be due to a small vortex or vortices within the tornado. These typically have much higher wind speeds than the tornado in general. This will be examined on the ground.

Only a few metres outside the areas of scoured earth, the ground is covered in grass and saffron thistle.

Unscoured earth
Scoured earth

The scoured earth has only the base tufts of grass.

The ground cover that was removed was mostly blown up against fences which were then ripped from the ground. This happened in paddocks on both sides of the highway.

Oxley Highway

The most obvious damage is on the Oxley Highway, 21km by road out of Coonabarabran and 85km from Gunnedah. In fact, the 85km to Gunnedah sign is within metres of the center of the damage.
 Vivian Evans has another wonderful page that vividly illustrates the change wrought by the tornado on the roadside vegetation along the Oxley. 

 

The schematic below shows the general pattern of damage at this point.

Highway damage sketch

The six photos below show the range of damage at the Oxley Highway crossing and the locations they were taken are identified on this diagram.

Locations of photos

1

Photo1
Photo2

2

3

Photo3
Photo4

4

5

Photo5
Photo6

6

End of the tornado

After crossing the Oxley Highway and scouring the paddock to the SE, the tornado lifted. This part of the tornado was also seen by Kelly Heaney of "Bullaway" who recorded several seconds of video. This will become available on the web page, but a (very poor) photograph off a tv screen was taken by Rob McNaught and is at least indicative of the general appearance. The rotation of the funnel is clear and a few leaves are seen falling in the vicinity of the camera.

The funnel lifts

The funnel lifting as recorded by Kelly Heaney.

Summary

With regions of heavy damage, this was not a weak tornado. The most common term used in television reports of tornadoes in Australia is "mini tornado" as if they are in some sense not real tornadoes. This reluctance to treat tornadoes seriously in the Australian media is probably a major reason why their occurence is largely underestimated by the public. Those who heard the roar of the tornado were quite sure of the power in its winds. Pat Redden of "Burloo" some 1km from where the tornado lifted described the sound as like a couple of jet aircraft roaring close by and Pat uses a hearing aid.

It seems probable that this tornado had periods of intensity reaching F1 or F2 (winds perhaps in the range 150-200km/hr) on the Fujita scale. Coupled with the width of up to 300m, this was as real a tornado as anyone would wish to see! It is perhaps fortuitous that there was no major property damage or loss of human life but the occupants of the car involved in the falling trees on the highway were clearly very shaken from all reports. It is possible that the tornado intensity dropped after hitting the roadside trees, as the paddock to the SE has no scouring adjacent to the highway. Perhaps this prevented the car from being lifted.

A graphic summary of the preliminary findings is given on the map below. This will be significantly updated over the weekend.

Map of sightings and damage

Acknowledgements

Many people have been extremely helpful in providing information. Pat and Esme Redden, Kelly and Mark Heaney, Charlie Harris, Vivian and Brian Evans and others that we hope to fully acknowledge later. Thanks to Andre Phillips for being our pilot. Cameron Henderson of the severe weather section of the Bureau of Meteorology (BOM) in Sydney provided useful feedback.

Rob McNaught, Tanya Smith and Gordon Garradd are all volunteer storm spotters for the BOM. Gordon in particular is very active and in a previous incarnation was the coordinator for severe storm volunteers in northern NSW, working then for the Uni. of New England in Armidale.

 

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